I. Field of the Invention: This invention relates generally to catheter apparatus for carrying out a variety of medical procedures and more particularly to an exchange catheter for facilitating the exchange of one catheter guidewire for another when required for effectively carrying out the catheterization procedure.
II. Discussion of the Prior Art: Since its introduction in the mid-1970's by Dr. Andreas Gruentzig, coronary transluminal angioplasty, using a balloon catheter, has become a recognized method for treating obstructed coronary blood vessels. In carrying out this procedure, an incision may typically be made in the patient's thigh to gain access to the femoral artery and an introducer is inserted into the wound. Next, a guiding catheter is passed through the introducer and routed through the vascular system until the distal end of the guiding catheter reaches the coronary ostium. Following that, a flexible guidewire is inserted through the guiding catheter until its distal end exits the distal end of the guiding catheter. The surgeon, by manipulating the proximal end of the guidewire, attempts to pass it across the stenotic lesion which is obstructing the coronary artery to be treated. Once the guidewire has been made to cross the lesion, a balloon angioplasty catheter is passed over the guidewire by inserting the proximal end of the guidewire into the distal end of the balloon catheter and then pushing the balloon catheter over the guidewire until the balloon on the distal end of the balloon catheter is adjacent the lesion to be treated. Once so positioned, the balloon is inflated to thereby press the stenotic lesion against the wall of the blood vessel and restoring patency to the treated blood vessel.
The above-described procedure assumes the use of a so-called over-the-wire balloon angioplasty catheter. A more recent innovation is the so-called Monorail.TM. catheter in which only a small distal segment of the balloon catheter actually passes over the guidewire with the remaining portion of the guidewire then extending generally along the exterior wall of the balloon catheter in the proximal direction. The Monorail.TM. catheter and its use is more particularly described in the Bonzel U.S. Pat. 4,762,129.
It frequently occurs during the conduct of a balloon angioplasty procedure that an originally selected guidewire may turn out not to be suitable for easily passing the stenotic lesion. It thus often becomes necessary to substitute an alternate guidewire. For example, to arrive at the site of the lesion, it may be necessary to employ a guidewire having a particular shape configuration on its distal end. However, with the guidewire so shaped, it may not easily traverse the lesion once the site is arrived at. Thus, the first catheter guidewire must be withdrawn and replaced with a second whose tip may more readily traverse the lesion.
The present invention is directed to a special purpose catheter for facilitating the exchange of guidewires used in angiography and/or angioplasty procedures using the Monorail.TM. catheter system. The exchange catheter is so designed that it can be used to transport the distal end portion of a new guidewire to the location within the vascular system reached by the distal end of the first guidewire by using the first guidewire as the rail along which the exchange catheter is routed. Once this maneuver has been accomplished, the first guidewire may be stripped out of the exchange catheter and the guide catheter containing it. Then, the exchange catheter itself can be withdrawn from the guide catheter without disturbing the replacement guidewire.
It is accordingly a principal object of the present invention to provide a new surgical tool for facilitating the conduct of transluminal angioplasty and/or angiography procedures.
Another object of the invention is to provide a surgical implement for facilitating the exchange of guidewires used during angiographic and angioplasty procedures.
Still another object of the invention is to provide an exchange catheter for use in a Monorail.TM. system for allowing a first selected guidewire to be replaced with a second guidewire without losing the positional advantage gained during the installation of the first guidewire. That is to say, using the apparatus and procedure of the present invention, it is no longer necessary to strip out the first guidewire from the guide catheter before the new guidewire is installed to the point where its distal end is at the location occupied by the distal end of the first guidewire before it is withdrawn.